1. The Field of the Invention
The present invention relates generally to endoscopic surgical instruments. Specifically, the present invention relates to surgical instruments that can selectively use both mechanical energy and electrical energy to remove tissue of a patient at an internally located surgical site. More specifically, the surgical instruments include a portion that operates in bipolar mode to cut, ablate, or cauterize tissues during an endoscopic procedure.
2. The Relevant Technology
Endoscopy is widely used in order to effect removal of unwanted or damaged tissues from a patient in a manner that is less invasive than completely opening up the tissue and using traditional cutting tools. The result is greatly shortened patient recovery, minimal scarring, reduced cost, elimination of typical pre-operative and post-operative hospital stays, and widespread use to correct a variety of injuries. A particular form of endoscopy, arthroscopy, is widely known and used to operate on joints, such as shoulders or knees.
An endoscope allows a doctor to look directly into a surgical site through a first incision, which allows for a minimally invasive procedure useful for both diagnosis and treatment. Typical endoscopes include a magnifying lens and coated glass fibers that beam an intense, cool light into the surgical site. The surgical field is viewed on a video monitor connected to an endoscopic video camera.
While viewing the surgical site in the manner described, the surgeon can perform any necessary repair and reconstruction using a separate surgical instrument inserted through a second incision at the surgical site. The surgical instrument can utilize a variety of mechanical cutting tools, such as rotating blades (straight or serrated) or burrs. Such mechanical cutting tools, or shavers, are well known in the art and require no further explanation. In general, rotating blades are generally used to excise unwanted or damaged soft tissues, while burrs are used on harder tissues such as bone.
The foregoing mechanical cutting or shaving tools are very useful for cutting and removing unwanted tissues in a less invasive and destructive manner compared to other surgical tools because they can be inserted through relatively small incisions that provide access to the surgical site. In this manner, they allow for a far less invasive and destructive surgery compared to typical surgical devices, which typically require far larger incisions and involve far higher destruction of perfectly healthy and normal tissues as the surgeon attempts to access the surgical site.
In addition to the aforementioned mechanical cutting tools, electronically powered cutting and cauterizing tools have been developed that also allow for less invasive surgical techniques than previous surgical tools. Such devices are known in the medical industry as either "monopolar" and "bipolar" devices. Both monopolar and bipolar devices have historically included a single positive, or lead, electrode that can be appropriately directed or situated to effect the cutting of soft tissues or cautery of bleeding vessels and tissues. Such devices have been referred to by some as "hot knives".
Whether a surgical electrode device is "monopolar" or "bipolar" depends on the location of the negative, or return, electrode. In a "monopolar" device, the return electrode is remotely connected somewhere else on the patient relative to the lead electrode. In this manner, the electrical current that is generated as a result of the application of a voltage potential to the lead electrode passes from the lead electrode through the tissue or blood vessel being cut or cauterized, through the intervening tissue of the patient's body, and to a grounding pad located remotely on the patient's body. Thus, a substantial portion of the pathway through which the current passes is the intervening tissue of the patient's body. However, since the current can be diffused over a relatively large area of tissue relative to the focused area where energy is applied by the lead electrode, the patient is not normally adversely affected by the passage of current through his or her body.
On the other hand, the return electrode in a "bipolar" device is located in the near vicinity of the lead electrode on the same surgical instrument. Typically, bipolar devices resemble tweezer-like structures comprising dual lead and return electrodes, although such devices are generally not used in endoscopic procedures. In practice, bipolar devices having a single positive lead have been used in a manner similar to monopolar devices in order to cauterize tissues.
Bipolar electrodes having multiple leads or positive electrodes have recently been developed that can be used to ablate or cauterize tissues soft tissues. Examples of multiple lead bipolar devices are set forth in U.S. Pat. Nos. 4,998,933; 5,178,620; 5,366,443; and 5,419,767, all to Eggers et al. (hereinafter the "Eggers et al. patents"). In general, multiple lead bipolar devices works by passing varying levels of high frequency electrical energy through individually powered multiple leads and into the tissue to be ablated or cauterized. The current that is generated as a result of applying voltage potentials to the multiple leads completes a circuit by returning to a single return, or common, electrode located on the same surgical instrument and connected to a ground by means of an insulated ground wire.
Due to its ability to destroy soft tissues by ablation, the multiple electrode bipolar devices can be used in a manner similar to mechanical cutters for removing unwanted or target tissues during an endoscopic procedure. However, multiple electrode bipolar devices have been found to be less efficient compared to single electrode bipolar devices in cauterizing tissues. Moreover, both monopolar and bipolar devices are limited by their inability to remove bone and the fact that they are less efficient and relatively slow in cutting or removing soft tissues compared to mechanical cutting tools. Nevertheless, they have found some use in a variety of surgical applications, as understood by those of ordinary skill in the art. For the ablative removal of relatively small amounts of soft tissues, multiple lead bipolar devices have proven useful.
Because both mechanical endoscopic surgical tools, such as rotary blades or burrs, and electronic devices, such as monopolar and bipolar devices, can be inserted through relatively small incisions to the surgical site, both mechanical and electrical devices can be used in succession and inserted through the same incision as the need arises to carry out a variety of desired surgical functions. For example, if the view of the surgical site has become obscured by excessive bleeding, sometimes caused by the mechanical cutting or shaving device, the surgeon can remove the mechanical cutting device from the incision and then insert through the same incision an electronic device in order to cauterize the bleeding tissue and blood vessels By removing the unwanted blood by known methods, vision to the surgical site can be restored or maintained.
Similarly, the surgeon might wish to utilize the various cutting or ablating features of the aforementioned monopolar and bipolar devices as needed as the surgery progresses in order to fine-tune the surgical process and remove the desired amount of damaged tissue in a desired manner.
While the various mechanical and electronic tools described above are useful in performing a variety of surgical functions, such as cutting, shaving, cautery, and ablating, their use requires the constant removal and insertion of at least two different tools, and possibly more, through the same incision. For example, if the surgeon wished to remove both hard and soft tissues from the same surgical site and/or cauterize and/or ablate tissues, the surgeon would have to insert and withdraw different surgical tools specially designed for performing the foregoing surgical functions. The constant insertion and removal of different surgical tools through the incision to the surgical site both complicates and lengthens the surgical procedure compared to if a single surgical instrument could be used.
In view of the foregoing, it would be an advancement in the art of the endoscopic surgery to provide a single surgical instrument that could simultaneously provide different surgical functions in order to eliminate or reduce the need to remove and insert different surgical instruments through the same incision.
It would be a further advancement in the art to provide a single surgical instrument that could be used to remove both hard and soft tissues at the surgical site as needed.
It would be an additional advancement in the art if the ability to remove both soft and hard tissues by a single surgical instrument could be performed selectively such that the means for removing hard tissue could be activated independently of the means for removing soft tissue.
It would yet be a further advancement in the art of surgery to provide a single surgical instrument that had the ability to more efficiently cauterize ruptured blood vessels or bleeding tissue in addition to removing either hard or soft tissues at the surgical site.
It would be an additional advancement in the art if the means for cauterizing tissue could be activated independently of either of the means for removing damaged or unwanted hard or soft tissues.
It would be a further advancement in the art of surgery to provide a single surgical instrument that provided the surgeon with the ability to electronically ablate soft tissues in addition to removing either hard or soft tissues by mechanical cutting or shaving.
It would be an additional advancement in the art if the means for ablating soft tissues could be activated independently of the means for removing damaged or unwanted hard or soft tissues by mechanical cutting or shaving.
Such multi-functional surgical instruments are described and claimed herein.